What parameters (number of turns, coil internal diameter, wire gauge) of a sensing coil should I use so that it does not distort the waveform? Could I use Spooky2 PEMF coil for this purpose?

Question added: “I would like to analyse a 50% duty cycle, 100% positive offset 30 KHz waveform transmitted through coil (50cm diameter). The transmitting coil would put out about 200-300nT magnetic Field.”

The lower the number of turns the better.

(The coil needs a low inductance.)

But the lower the inductance to lower the Output Voltage.

(200-300nT is very low. The Earth static magnetic field is about 40uT and this is problematic to measure.)

Spooky2 PEMF coil has an inductance of 200uH. This comes to a blind Resistance of 37 Ohm at 30 kHz.

But this will distort the measured Waveform. Not really useful.

I assume that you need an external Pre-Amplifier (factor 1000x) for your Oscilloscope that amplify the output of the sensing coil (that may have with one or two turns).

For more details, please check the link from:
https://www.spooky2.com/forums/viewtopic.php?f=39&t=10629